A call for help from the survivors of a dying world... an incredible world that has been flying through space for 900 years, with contrasting inhabitants. Some have never changed; others have reverted to barbarism. But can this offer new hope for the Alphans? ITC summary

The Daria is based on a 1971 painting by NASA artist Robert McCall (1919-2010), titled "Aerospace Port". It is one of a series of paintings of massive cities floating in the sky over Arizona landscapes.

The Daria was designed by both Brian Johnson and Martin Bower, and built in sections by Bower. One of the details on the top is a cap from NDA 2 (Breakaway). Many of the sections were used in the Delta spacestation seen in Into Infinity. The dome on top became a Moonbase building (the transference dome in Journey To Where, and in other episodes).

The larger section with which the Eagle docks is surrounded by borders seen as the interior of the Atherian shuttle in Collision Course.

There are 3 matte shots (2 of the gantry over the civilised part of the ship, 1 of the jungle).

Transplant surgery. The first organ transplant was a kidney in 1954; now there are routine procedures for kidneys, bone marrow, skin grafts, cornea, lungs, livers and hearts. There are still problems with tissue rejection as the immune system identifies foreign cells, and the vulnerability to infection caused by the drugs that suppress the immune system. Already demand exceeds supply, and many countries (for instance, India) allow healthy people to sell their organs commercially. There have been numerous stories since the 1970s of healthy people being kidnapped or murdered for organ harvesting, especially in third world countries. Small grafts can rejuvenate the brain and central nervous system (fetal tissue is one controversial area of research). The technology, and ethical issues, are thus soundly based.

The double helix of DNA was discovered by Watson and Crick in 1953. DNA is a long molecule consisting of four bases (like the letters in a computer program). Two complementary strands of DNA are wrapped around each other, with each of the nucleotide bases being paired (Adenosine to Thymine, Guanosine to Cytosine). The base pairing of the structure is the key to its stability and the ability to make perfect copies (when the strands are unwound, the unpaired bases are templates for DNA polymerase enzymes to create new strands). The ability to replicate identical copies is how genetic inheritance works. There are other structures. Bacteria cells (prokaryotes) have a single circular DNA molecule. Viruses can have DNA or RNA, double or single stranded, circular or linear.

Props:

"Is it not true that your own planet, Earth, may also no longer exist?" asks Neman and Koenig agrees. This possibly contradicts Another Time, Another Place (which was a possible future Earth).

The Daria is 20 miles long by 5 miles wide- a 100 square miles. When they are flying along the length of the ship, Koenig says "there's fifty miles of ship... Keep trying." Thanks to Elliot.

Lowry has a habit of holding his commlock on his belt- so that the five intact fingers of his hand are sometimes visible. When the Priest holds up his hand, it is a body double whose finger was amputated at the second joint. The next shot shows a finger that stops at the first joint - probably Paul Antrim's real hand, with the top of his finger taped back.

The story is reportedly based on how survivors of a plane crash in the Andes eat dead bodies. The book, Alive by Pier Paul Read, was published in 1975 and made into a film in 1993. It told how in October 1972 the plane carrying 45 people including the Montevideo Old Christians Rugby team crashed. 31 survived the crash, but it was ten weeks before the survivors were located, by which time just 16 were alive.

The name Darian recalls the Dorian invaders who overthrew the Mycenean civilization about 1000 BC and established classical Grecian civilisation based on militaristic city states. The Grecian-inspired togas and hairstyles emphasise this.

Hadin is named after Skarp-Hedin, a son of Njal, hero of the 13th century Icelandic Njal's saga. The Viking elite wore clothes that also resembled the Darian fashions.

Another source was Brian Aldiss's book Nonstop (also called Starship), a 1968 book which was in turn inspired by Robert Heinlein's Universe (1941). "Generation starships" were first proposed by Russian scientist Konstantin Tsielkovsky in 1928 and became a science fiction staple after Don Wilcox's 1940 book The Voyage That Lasted 600 Years.

How do mutants like the dwarfs grow to maturity? Wouldn't they be killed as children or are they kept alive deliberately?

If the Darians lack essential components- how does the ending give them the trace elements and enzyme variants?

The tune that Lowry whistles is "A Wandering Minstrel" by Gilbert and Sullivan (thanks to Matt Butts)

In the Level 7 set, pieces of furniture that previously appeared in The Infernal Machine (in red) appear: the Pastilli chair (two black ones either side of the Spirit doors, three others in the camp) and the Ditzel barstool (immediately in front of the doors).

Ray Austin: The only time I had trouble with Barbara Bain. The first morning Joan Collins came on the set, her skirt was shorter than Barbara's... and she went mad off camera. She went to see Gerry and Sylvia, said "I'm not going to have it." She wanted her skirt shorter than Joan Collins - Joan Collins' skirt had to be lengthened. She (Collins) was a fantastic woman, that's why we employed her. But 'Barbara Pain' as the crew used to call her, she wanted wardrobe to change Joan Collins' skirt but Gerry said no, that's why we've got her, we're not going to hide her legs. That's why that outfit was designed." (Anderson #13, Feb 2012, p12)